Single cutter die



March 22, 1938. J. D. TUCKER 2,

SINGLE CUTTER DIE Filed May 14, 1937 INVENTOR J. D. Tu 'cjcer BYQV' ATTORN EY Patented Mar. 22, 1938 SINGLE CUTTER DEE Jesse 1). Tucker, North Sacramento, Calif., as-

signor to Tucker Gilmore Manufacturing Company, a corporation Application May 14, 1937, Serial No. 142,584

3 Claims.

"Thisinvention relates to thread cutting dies and particularly represents improvements over the die shown in my Patent No. 2,052,587, dated September 1, 1936.

The main object of the present invention is to retain all the advantages of the previous die, while arranging the steady rest block so that it has a better centering and holding action on the part being threaded than in the previous device, and which is designed so that the possibility of scratching the metalor chipping the threads as they are cut is avoided.

Also the leading end of the cutter block of the die is formed with a lip of such a shape that the use of lubricant in the operation of the die is rendered unnecessary, which is especially of value when working copper and the like.

The figure on the drawing is a front face View of my improved die. 20 Referring now more particularly to the characters of reference on the drawing, the body 5 of the die is cylindrical as usual to fit in and be engaged by a conventional chuck or stop, the body being provided with a central opening ll. Mounted in sockets 2 and 3 formed in the body and disposed in diametrally opposed relation to the opening are cutting and steady rest blocks d and 5 respectively. The adjacent ends of these blocks project into the opening El and as usual they are mounted in the sockets for slight longitudinal adjustment.

The inner face of the cutter block l is formed with thread sections 6 which gradually increase in depth along the block as is common practice, so that the threads as cut in the bolt etc. will be gradually increased to the full desired depth from the inception of the cut. The arcuate'extent of the cutting threads is approximately 100, with the greater proportion of such are on the leading side of the median line 1 of the blocks as shown.

The radius of the thread sections is the same as that of the bolt to be threaded, but the thread are is disposed slightly eccentric or offset from said median line I, said are diverging from the leading end L to the trailing end of the cutter relative to the bolt circle.

The adjacent face of the opposed rest block 5 is threaded as at t on the same radius as the threads 6, but centered on the line i. The threads 8 increase in depth from the outer end of the block in the same manner as the threads 6, and are in position to properly cooperate with said threads 5 so that they will enter the thread grooves in the bolt as cut by the threads 6. As

in the previous die however it is to be under stood that the threads 8 are not cutting but guide threads only, having a close fit with the cut threads. This maintains the threads as cut in perfect alinement and counteracts any tendency of the thread to lead. The arcuate extent of the guide threads 8 is considerably greater than that of the cutting threads, and approximately 135.

- The leading end of the rest block and of its threads lies approximately in a line 9 drawn at right angles to the line "i and intersecting the center of the threads 8, so that they are approximately 45 from the trailing end of the cutter threads. With the guide threads being approximately l35 in extent, the trailing end of the rest block threads is thus disposed approximately from the leading end L of the cutter threads.

By reason of this arrangement the bolt or the like being threaded is supported and braced at a point directly opposite to and even beyond the leading end L of the cutter threads, so that such bolt is adequately held in engagement with the cutting threads in the inception of the cut as is desired. The belt is also of course steadied at all points opposite the entire arcuate extent of the cutting block and its threads.

The leading end of the rest block being blunt or radially cut, scratching or chipping of the threads as they are cut in the bolt is avoided. This feature is aided by the proximity of said end of the rest block to the adjacent end of the cutter block, which prevents any possibility of lateral deviation of the bolt out of axial alinement with the rest threads.

The leading end ofthe cutter block is formed relative to the thread circle as a sharp tapering lip-as shown, which facilitates the entry of the threads into the metal and avoids the need of lubricant which is undesirable with certain metals.

The opening it is enlarged outwardly of the blocks on the leading side of the cutter block as shown at IE! to provide for the escape of the chips, such enlargement being actually unnecessary on the opposite side so that the body l is never unduly weakened even though the enlargement it] is made of considerable size as may be desirable to facilitate the free discharge of the chips.

By reason of the specific features of construction of the die as recited, it is much easier to start than the conventional die, the threads on the steady rest block acting as locators and feed the threads in Without stripping, which is especially advantageous at the start.

From the foregoing description it will be readily seen that I have produced such a device as substantially fulfills the objects of the invention as set forth herein.

While this specification sets forth in detail the present and preferred construction of the device, still in practice such deviations from such detail may be resorted to as do not form a departure from the spirit of the invention, as defined by the appended claims.

Having thus described my invention, What I claim as new and useful and desire to secure by Letters Patent is:

1. A thread cutting die including a supporting body, cutting and steady rest blocks mounted in the body in opposed relation to each other, and cutting thread sections extending about the inner face of the cutting block, the inner face of the steady rest block being shaped to follow the contour of and engage a portion of the circumferential surface of the member being threaded and the leading end of said face being disposed ahead of a line drawn diametrally from the leading end of the thread sections.

2. A die as in claim 1 in which the rest block at its leading end is out radially of the circle of said inner face thereof.

3. A thread cutting die including a supporting body, cutting and steady rest blocks mounted in the body in opposed relation to each other, and cutting thread sections extending about the in nor face of the cutting block and having an arcuate extent of substantially 100, and guide thread sections extending about the inner face of the steady rest block and having an arcuate extent of 135"; the trailing and leading ends of the cutting and guide threads respectively being spaced apart substantially 45.

JESSE D. TUCKER. 

